“Stay strong, Keaton. Don’t let them make you turn cold. I promise it gets better,” the Captain America actor, 36, tweeted on Sunday, December 10. “While those punks at your school are deciding what kind of people they want to be in this world, how would you and your mom like to come to the Avengers premiere in LA next year?”

Stay strong, Keaton. Don’t let them make you turn cold. I promise it gets better. While those punks at your school are deciding what kind of people they want to be in this world, how would you and your mom like to come to the Avengers premiere in LA next year? https://t.co/s1QwCQ3toi

Keaton made headlines after his mother, Kimberly Jones, shared an emotional video on Facebook on Friday, December 8, of her tearful son explaining how he was bullied at school. “They make fun of my nose. They call me ugly. They say I have no friends,” he said. “Just out of curiosity, why do they bully? What’s the point of it? Why do you find joy in taking innocent people and finding a way to be mean to them? It’s not OK. … People that are different don’t need to be criticized about it. It’s not their fault.”

Kimberly wrote in the caption of her post that Keaton asked her to record and share the video after she picked him up from school “because he was afraid to go to lunch.”

Several celebrities rallied around Keaton with messages of support. “Keaton baby, just know you’re not alone. There are so many people who come out of bullying so much stronger and you will be one of them!! God bless you sweetheart,” Demi Lovato tweeted on Sunday. In a video message on Instagram, Justin Bieber said, “The fact that he still has sympathy and compassion for other people when he’s going through it himself is a testament to who he is. This kid is all-time. He’s a legend.”